In order to remain competitive, telephone service providers must continually make available new service offerings and service features to subscribers. Implementing new features using the Common Channel Signaling (CCS) network has several limitations familiar to those skilled in the art.
A major hindrance to the provisioning of new service offerings and service features involves inherent limitations in the flexibility and extensibility of the CCS network. The CCS network in North America is a Signaling System 7 (SS7) network. The CCS network supports the establishment of two-party calls with Integrated Services Digital Network-User Part (ISUP) messaging and database queries with Transaction Capabilities-Application Part (TCAP) messaging.
The SS7 protocol was designed at a time when two-party call control was a primary focus of the designers. Because of the structure of the CCS network it can be expensive to enable new services that are dependent on common channel signaling. The SS7 signaling protocols conform to international standards that have limited flexibility. The number of CCS network elements that would have to be modified in order to improve flexibility and enable significant extensions to the protocol is prohibitive. Besides, parts of the CCS network are reported to be experiencing signaling congestion. Alleviating signaling congestion, and introducing content/service messaging are both difficult within the confines of the fixed 64 KB/s transmission rate of the CCS network. Furthermore, any functionality that requires the transfer of data at a rate greater than 64 KB/s cannot be realized within the CCS network.
Transaction Capability-Application Part (TCAP), and its derivative Intelligent Network-Application Part (INAP), are protocols used in the CCS network. TCAP and INAP messages are the traditional carriers of service feature functionality. TCAP and INAP suffer the same limitations as the other signaling protocols used in the CCS network. Apart from the fact that these signals are conveyed at 64 KB/s, they are also limited by their inflexibility. The TCAP and INAP messages are designed to facilitate the querying of databases and responding to the queries with call routing information. The content carried by a TCAP or INAP message cannot be extended, nor can an interpretation of a message's content be modified without substantially modifying many CCS network elements.
Of particular interest for the provision of content or services to subscribers, is the ability to remotely interface with the bearer channel of subscriber lines. However, the bearer network, whether circuit- or packet-switched, is the only network designed to access the bearer channel of a subscriber line. Since interaction with a subscriber requires access to the bearer channel of the subscriber's line, such functionality is not available to devices that access only the CCS network. Nor is such functionality available to elements of the bearer network, unless those devices can be remotely accessed from the call control channel.
The method currently used to enable interaction with subscribers during call processing uses Intelligent Peripherals, which are typically connected to service switching points (SSPs) by Integrated Services Digital Network (ISDN) trunks. Although Intelligent Peripherals (IPs) permit interaction with subscribers for the purpose of collecting information, useful in making call routing decisions, etc., their use has several disadvantages. In order to use the resources of IPs, a call must first be terminated to the IPs. After the information is collected, the calls to the IPs must be released and new calls initiated using routing information collected, without releasing the calling party. This is time consuming and requires a feature-rich SSP, as well as a complex network control element, such as a Service Control Point (SCP). Furthermore, the installation of IPs requires a great deal of circuit-switched resources that may be idle most of the time.
There therefore exists a need for flexible content/service messaging, to enable extensible service features, and content provision to telephone service subscribers. There also exists a need for a system to permit the provision of content or services to a telephone service subscriber that permits services or content to be delivered economically by directly accessing a bearer channel for the telephone service subscriber.